A new tool for genotoxic risk assessment: Reevaluation of the cytokinesis-block micronucleus assay using semi-automated scoring following telomere and centromere staining.

BACKGROUND: The cytokinesis-block micronucleus (CBMN) assay is an internationally recognized method for measuring DNA damage after exposure to genotoxic agents, as well as a biomarker for DNA repair and chromosomal instability. The high baseline level of micronuclei (MN) in the healthy population has limited the sensitivity and application of the CBMN assay for the follow-up of exposed populations. We reevaluated the sensitivity of the CBNM assay using semi-automated MN scoring following telomere and centromere (TC) staining after in vitro exposure to genotoxic agents (mitomycin or radiation) or aneugenic agents (vinblastine). MATERIALS AND METHODS: Blood samples from 12 healthy donors were exposed to 137Cs at seven doses from 0.1-4 Gy and cultured for 72 h. Cytochalasin B was added at 46 h of culture. The exposure of chemical agents (mitomycin or vinblastine) was performed after 48 h of culture for 3 h. Cytochalasin B was added after treatment and slides were prepared 24 h after. MN was semi-automatically scored following TC staining. Nucleoplasmic bridges (NPBs) and nuclear buds (NBUDs) were assessed in a human cell line after TC staining. RESULTS: The introduction TC staining to the scoring of MN not only renders MN scoring more efficient and robust, but also permits discrimination between exposure to clastogenic (MN with only telomere signals) and aneugenic agents (MN with both TC signals). The resulting improvement of MN detection led to an increase in the sensitivity of the CBMN assay following low-dose radiation exposure (0.3 versus 0.1 Gy). Hyperradiosensitivity phenomenon was observed after low dose exposure. A dose-response curve was obtained for up to 4 Gy. In addition, TC staining permits assessment of the nature of NPBs and NBUDs as biomarkers for genotoxicity and chromosomal instability. CONCLUSION: These approaches can be potentially used to follow-up populations exposed to genotoxic agents and assess cancer risk.

Report from the Rockefellar Foundation Sponsored International Workshop on reducing mortality and improving quality of life in long-term survivors of Hodgkin's disease: July 9-16, 2003, Bellagio, Italy.

A workshop, sponsored by the Rockefellar Foundation, was held between 9 to 16 July, 2003 to devise strategies to reduce mortality and improve quality of life of long-term survivors of Hodgkin's disease. Participants were selected for their clinical and research background on late effects after Hodgkin's disease therapy. Experts from both developed and developing nations were represented in the workshop, and efforts were made to ensure that the proposed strategies would be globally applicable whenever possible. The types of late complications, magnitude of the problem, contributing risk factors, methodology to assess the risk, and challenges faced by developing countries were presented. The main areas of late effects of Hodgkin's disease discussed were as follows: second malignancy, cardiac disease, infection, pulmonary dysfunction, endocrine abnormalities, and quality of life. This report summarizes the findings of the workshop, recommendations, and proposed research priorities in each of the above areas.